The disclosure relates to a linear actuator which serves to move a load. One preferred field of use is movement systems such as driving simulators and flight simulators, in which a cab is mounted on a platform which can be moved in six degrees of freedom by a total of six identical linear actuators. Linear actuators are known which have a tubular actuator housing which has an end-side housing bottom and an end-side housing head, a rotatably drivable threaded spindle which is mounted rotatably in the housing bottom of the actuator housing and extends in the interior of the actuator housing from the housing bottom in the direction of the housing head, a piston which comprises a spindle nut, which is in engagement with the threaded spindle, and is guided longitudinally in the actuator housing, and a hollow actuator rod which is assembled with the spindle nut, into which actuator rod the threaded spindle dips, and which actuator rod protrudes out of the actuator housing on the housing head.
It is also known to equip a linear actuator of this type with means for compensating for the static load, up to 75% of the static load being supported, for example, by way of said means. The remaining proportion of the load is absorbed by the threaded spindle. If a plurality of linear actuators are provided to carry the load, each linear actuator of course accepts only a certain proportion of the load. If desired, up to 100% of the static load can also be compensated for.
In a known linear actuator of the type depicted, the means for at least partial compensation of the load operate like a pneumatic spring. The tubular actuator housing is surrounded by a further tube, with the result that an annular space is configured which is divided by way of a piston into a gas space and into an oil space which is connected fluidically to the interior of the actuator housing. The entire interior space of the actuator housing and the interior of the hollow actuator rod which is connected fluidically to the interior space of the actuator housing by way of small radial bores close to the piston are filled with oil. The piston has ducts, via which the part volumes on both sides of the piston are connected fluidically to one another, with the result that oil can be exchanged between the part volumes.
In the known linear actuator, the means for compensating for the load therefore correspond to a hydropneumatic piston accumulator which is assembled in a highly integrated manner with the actual linear actuator.